US9031420B2 - Digital optical coherent transmission device - Google Patents
Digital optical coherent transmission device Download PDFInfo
- Publication number
- US9031420B2 US9031420B2 US13/759,214 US201313759214A US9031420B2 US 9031420 B2 US9031420 B2 US 9031420B2 US 201313759214 A US201313759214 A US 201313759214A US 9031420 B2 US9031420 B2 US 9031420B2
- Authority
- US
- United States
- Prior art keywords
- signal
- amplitude
- constellation
- optical
- appropriate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active, expires
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
- H04B10/61—Coherent receivers
- H04B10/616—Details of the electronic signal processing in coherent optical receivers
- H04B10/6165—Estimation of the phase of the received optical signal, phase error estimation or phase error correction
Definitions
- the following embodiments are related to a digital optical coherent transmission device.
- One of the means for solving the problems is a digital optical coherent transmission system which has recently attracted attention as an improvement of the tolerance against the waveform distortion of an OSNR and a transmission line (D. Ly-Gagnon, IEEEE JLT, pp. 12-21, 2006).
- FIG. 1 is an example of a configuration of a digital optical coherent receiver.
- the digital optical coherent receiver detects signal light and local light from a local light source 10 at 90° hybrid circuits 12 - 1 and 12 - 2 after splitting the light into each polarizing axis through polarization beam splitters 11 - 1 and 11 - 2 .
- O/E converters (optical/electrical converters) 13 - 1 through 13 - 4 are provided to convert an optical signal corresponding to the amplitude and the phase of the optical signal output from the 90° hybrid circuits 12 - 1 and 12 - 2 into an electric signal.
- A/D converters 14 - 1 through 14 - 4 for quantizing an electric signal are provided, and a DSP (digital signal processor) 15 is provided to compensate for a waveform distortion and demodulate a signal using quantized digital data.
- the polarization beam splitters 11 - 1 and 11 - 2 , the 90° hybrid circuits 12 - 1 and 12 - 2 , and the O/E converters 13 - 1 through 13 - 4 configure an O/E converter 16 (an O/E converter corresponding to 25 ( FIG. 9 ) on the receiving side).
- the digital optical coherent transmission system extracts the optical intensity and the phase information by the coherent transmission system. Then, by quantizing the extracted optical intensity and the phase information by the ADC, the digital signal processing circuit demodulates them. Therefore, the present invention corresponds to a multivalued modulation system such as M-ary PSK (phase shift keying), QAM (quadrature amplitude modulation), etc. and a frequency division multiplexing system such as FDM (frequency division multiplexing), OFDM (orthogonal frequency division multiplexing), etc.
- M-ary PSK phase shift keying
- QAM quadrature amplitude modulation
- FDM frequency division multiplexing
- OFDM orthogonal frequency division multiplexing
- One of the degradation factors of the signal quality of the digital optical coherent receiver is amplitude variance of a signal of each channel.
- the factor of the occurrence of the variance of the signal amplitude of each channel may be a difference of an individual component such as an electric line forming the route of each channel, a 90° hybrid circuit, an O/E, etc.
- FIGS. 2 through 4 illustrate the relationship between the quality of an A/D converted signal and the amplitude of an ADC input signal.
- FIGS. 2 and 3 illustrate the difference by the presence/absence of the variance of the signal amplitude between an in-phase (I) signal and a quadrature (Q) signal. Relating to the arrangement of the signal on the IQ constellation map, FIG. 2 illustrates in the part (a) the ideal state of the IQ signal, and FIGS. 3 and 4 illustrate in the respective parts (a) the state in which there occurs a variance of signal amplitude.
- FIGS. 2 , 3 , and 4 The outline of the A/D conversion of a signal in each state in FIGS. 2 , 3 , and 4 in their respective parts (a) is illustrated in FIGS. 2 , 3 , and 4 in their respective parts (b).
- FIG. 2 illustrates in the part (a) the ideal state in which the signal amplitude is appropriately input as an ADC input amplitude between the I and the Q signals.
- the signal information is not largely impaired even after the signal is quantized as a digital signal.
- FIG. 3 illustrates the excessive stage of the signal amplitude in the part (a).
- the signal amplitude is excessive, the amplitude is expressed as a rectangular shape on the constellation map. That is, the I and Q signals exceed the upper limit of the output of the ADC, and are limited. Therefore, the signal is cut at a value in the I and Q directions.
- the part (b) of FIG. 3 since the signal information in the area in which the input signal exceeds the range of the resolution of the ADC is lost during the quantization, there occur the sensitivity degradation of the ADC and the erroneous determination in the digital signal processing as a result.
- FIG. 4 illustrates in the part (a) the state in which the signal amplitude is excessively small.
- the part (b) of FIG. 4 since the effective area of the resolution of the ADC becomes smaller, the signal information is lost during the quantization, and there occur the sensitivity degradation of the ADC and the erroneous determination in the digital signal processing as a result as in the case of the excessive amplitude.
- skew delay time difference
- the factor of the occurrence of the skew may be the individual difference of each of the components such as the electric line for the route of each channel, the 90° hybrid circuit, the O/E, the ADC, etc. up to the input stage of the DSP (digital signal processor).
- DSP digital signal processor
- FIGS. 5 and 6 illustrate the relationship between the regeneration quality of a signal and the skew.
- the DP-QPSK system is exemplified.
- FIGS. 5 and 6 illustrate the difference by the presence/absence of the skew between the I and Q signals.
- the parts (a) of FIGS. 5 and 6 exemplify the timing relationship between each signal and the ADC sampling.
- the parts (b) of FIGS. 5 and 6 exemplify the arrangement of the signals on the IQ constellation map.
- FIG. 5 illustrates an ideal state indicating no skew between the I and Q signals. As illustrated in the part (a) of FIG. 5 , each of the I and Q signals is sampled with the same phase timing in the ADC, and the signal point is arranged at four points by the combination of the phase state as illustrated in the part (b) of FIG. 5 .
- FIG. 6 illustrates the case in which there occurs the skew between the I and Q signals.
- the Q signal is behind the I signal by ⁇ , it is sampled with the timing deviating from the point at which the sampling is to be performed (white point in the part (a) of FIG. 6 ).
- the signal is arranged at a point different from the original position as illustrated in the part (b) of FIG. 6 .
- the digital optical coherent transmission device is a device in an optical transmission system using a multivalued modulation method or a frequency division multiplexing method is provided with: an O/E converter which optical-coherent-receives a received optical signal and converts the optical signal into an electric signal; an analog/digital conversion unit which converts the electric signal from the O/E converter into a digital signal; a first constellation acquisition unit which acquires first constellation information for the output digital signal of the analog/digital conversion unit; and an amplitude control unit which controls amplitude of the electric signal from the O/E converter when it is determined according to the first constellation information that the amplitude of the output digital signal is not appropriate.
- the following embodiments may provide a digital optical coherent transmission device capable of improving the degradation of signal quality.
- FIG. 1 is an example of a configuration of a digital optical coherent receiver
- FIG. 2 is a view (1) illustrating the relationship between the quality of the A/D converted signal and the ADC input signal amplitude
- FIG. 3 is a view (2) illustrating the relationship between the quality of the A/D converted signal and the ADC input signal amplitude
- FIG. 4 is a view (3) illustrating the relationship between the quality of the A/D converted signal and the ADC input signal amplitude
- FIG. 5 is a view (1) illustrating the relationship between the regeneration quality of a signal and skew
- FIG. 6 is a view (2) illustrating the relationship between the regeneration quality of a signal and skew
- FIG. 7 is an example of the method of determining whether or not an A/D converted signal is in the optimum range on the constellation map
- FIG. 8 is an example of the method of determining whether or not an A/D converted signal is in the optimum range on the constellation map
- FIG. 9 is a block diagram of the digital optical coherent transmission system according to an embodiment of the present invention.
- FIG. 10 is a flowchart of the entire process according to an embodiment of the present invention.
- FIG. 11 is a flowchart of the process of the amplitude control amount determination unit in FIG. 9 ;
- FIG. 12 is a flowchart of the process of the EVM determination unit in FIG. 9 .
- the information about the constellation map of a signal is acquired at the input stage of the signal from the ADC to the digital signal processing unit and the output stage of the digital signal processing unit, and the amplitude of the signal and the skew are corrected using the information.
- FIG. 7 is an example of the method of determining whether or not an A/D converted signal is in the optimum range on the constellation map.
- the mask A indicates a square which passes the coordinates m, -m, n, and -n on the constellation map.
- m and n are output upper limit values of the I and Q signals of the ADC.
- the mask B indicates a circle which passes the coordinates m, -m, n, and -n or a polygon formed by 8N points on the constellation map.
- the mask C indicates a circle which passes the coordinates m/2, -m/2, n/2, and -n/2 or a polygon formed by 8N points on the constellation map (N indicates any number).
- a circle causes a complicated process in the digital processing, for example, an 8N polygon is used as a form approximate to a circle.
- a circle is an ideal form, it is preferable that a circular mask is used if a circular mask is easily processed.
- the coordinates of the mask C are values using m/2 and n/2, the values are not restricted, and the exemplified coordinates of m and n are expressed by m/2 and n/2 values.
- the number of signal points distributed in each mask is counted, and the respective ratios are calculated. That is, (number of distributed points in mask A)/(number of distributed points in mask B) is used as a value for determination of the occurrence of an excessive amplitude, and (number of distributed points in mask C)/(number of distributed points in mask B) is used as a value for determination of the occurrence of a too small amplitude.
- the ratio of the number of distributed points in mask A to the number of distributed points in mask B is, the closer to the optimum state the amplitude gets. In addition, the larger than 1 the ratio is, the closer to the excessive state the amplitude becomes.
- the ratio of the number of distributed points in mask C to the number of distributed points in mask B is smaller to a certain extent than 1, the amplitude is closer to the optimum state. If it is closer to 1, the ratio is closer to a too small amplitude state. Using the relationship, the ratio is compared with a specified threshold, thereby determining whether or not there occurs an excessive amplitude or a too small amplitude.
- the threshold is set to 1. Since the ratio for determination of a too small amplitude indicates a too small amplitude when the threshold is a value smaller to some extent than 1, a value smaller to some extent than 1 is to be set.
- the threshold smaller than 1 is obtained by changing the output amplitude of the ADC, and by measuring the bit error rate of an obtained signal, when a device is designed, thereby determining the level of the threshold which has no undesired influence on the bit error rate through an experiment.
- FIG. 8 is an example of the method of determining whether or not an A/D converted signal is in the optimum range on the constellation map.
- the EVM is calculated by calculating the constellation on the measurement signal, and by obtaining the difference (error vector) in vector between the measurement signal and the reference ideal signal.
- the difference in vector By obtaining the difference in vector, the amplitude direction of a measurement signal and the error in the phase direction may be expressed by numbers, and the signal quality of the measurement signal may be quantitatively expressed.
- the measurement signal (IQ actual measurement) and the reference ideal signal (IQ reference) are plotted on the IQ plane of the constellation, and the difference is defined as an error vector.
- the EVM of the n-th symbol is calculated as follows from the I component (I error (n)) and the Q component (Q error (n)) of the error vector.
- the amount of correction of the amplitude of the I and Q signals is obtained from the I and Q component of the error vector, and the amount of correction of the skew is obtained from the phase difference between the IQ actual measurement and the IQ reference.
- FIG. 9 is a block diagram of the digital optical coherent transmission system according to the present embodiment.
- a framer processing unit 20 on the transmission side terminates the signal input from the client side.
- An encoding unit 21 adds an error correction code to the signal.
- a multiplexing unit 22 multiplexes a signal for associating the signal with the optical phase and the polarization, and generates I and Q signals for each of the X polarization and the Y polarization.
- An E/O conversion unit 23 is provided with an optical modulator etc. for performing electrical/optical conversion.
- a local light source 24 on the reception side generates local light for coherent detection.
- An O/E converter 25 is a configuration for optical/electrical conversion, and has the same configuration as the O/E converter 16 illustrated in FIG. 1 .
- An analog/digital conversion unit (ADC) 26 digital-converts the input analog signal.
- a digital signal processing unit (DSP) 27 demodulates the signal by the digital signal processing.
- An error correction decoding unit 28 corrects an error of a signal from the added error correction code.
- a deframer processing unit 29 decomposes the frame and transmits the signal to the client side.
- a capture unit A 30 for extracting the IQ constellation after the A/D conversion is provided at the input stage of the DSP unit 27 .
- a capture unit B 31 for extracting the IQ constellation of the signal demodulated by the digital signal processing is also provided at the output stage of the DSP unit 27 .
- an amplitude control unit 33 Based on the IQ constellation information (inter-signal variance) detected by the capture unit A 30 , an amplitude control unit 33 compensates for the signal amplitude at the output stage of the O/E converter 25 through an amplitude control amount determination unit 32 . Since the O/E converter 25 normally has the function of adjusting the amplitude of the electric signal to be output in the circuit of converting an optical signal into an electric signal, the amplitude control unit 33 uses the function to adjust the amplitude of the output electric signal of the O/E converter 25 .
- a skew control unit 35 Based on the IQ constellation information (inter-IQ skew information) detected in the capture unit B 31 , a skew control unit 35 performs inter-IQ skew compensation at the output stage of the O/E converter 25 and at the output stage of the multiplexing unit 22 on the transmission side through an EVM determination unit 34 .
- the EVM determination unit 34 compensates for the amplitude error of the I and Q signals through the amplitude control unit 33 .
- the EVM determination unit 34 calculates the above-mentioned error vector, calculates the amplitude error and the phase error of the I and Q signals, and provides the amplitude control unit 33 and the skew control unit 35 with the result of the calculation as an amount of correction, thereby correcting the amplitude and the skew.
- the correction of the skew is made by providing a delay element at the electric stage in the O/E converter 25 on the reception side and providing an appropriate delay for the electric signal. Similarly, a delay element is provided at the electric stage in the multiplexing unit 22 on the transmission side, and an appropriate delay is provided for the electric signal.
- the IQ constellation information is acquired by holding the combination of the signal value of the I signal and the signal value of the Q signal as the coordinates of the I-Q plane in any of the capture unit A 30 and the capture unit B 31 .
- the method of transmitting the control signal for skew control from the skew control unit 35 on the reception side to the multiplexing unit 22 on the transmission side it is considered to use the GCC (general communication channel) in an OTN (optical transport network) frame.
- GCC general communication channel
- OTN optical transport network
- the capture unit A 30 acquires the constellation information for detection as to whether or not the amplitude of the output signal of the ADC 26 is appropriate.
- the constellation information acquired by the capture unit A 30 is a set of the information whose signal points have been variously rotated, expanded, and reduced in the I-Q plane due to the degradation etc. in the transmission line of a signal value. Therefore, it is determined as to whether or not the amplitude of the vector obtained from the I and Q signals of the signal value is appropriate relating to the constellation information at the capture unit A 30 .
- the capture unit B 31 is additionally provided. The capture unit B 31 generates the constellation information with the signal value after the demodulation by the DSP 27 .
- the constellation information uses the signal value after the demodulation, one signal point for each quadrant of the I-Q plane appears in the case of the QPSK. Therefore, by comparing the signal point with the position of the ideal signal point, the balance of the amplitude of the I and Q components and the phase error may be detected. Therefore, the constellation information about the capture unit A 30 is used for appropriate correction of the output of the ADC 26 so that the demodulation at the DSP 27 may be correctly performed. On the other hand, the constellation information about the capture unit B 31 is used for correction of the error of the amplitude and the skew for the improvement of the bit error rate at the reception end.
- FIG. 10 is a flowchart of the entire process according to the present embodiment.
- two polarization axes (X axis and Y axis) are orthogonal to each other.
- step S 10 the optimum range and error tolerance range of each IQ constellation to be detected in the capture unit A 30 and the capture unit B 31 are set.
- step S 11 the IQ constellation of each of the X polarization and the Y polarization is extracted using the capture unit A 30 is extracted, and is held as an acquired value.
- step S 12 it is determined using the determining method as illustrated in FIG. 7 whether or not the amplitude of the acquired value of each signal in the IQ constellation is in the preset optimum range. If it is determined in step S 12 that the amplitude is not in the optimum range, then the compensation is performed through the amplitude control unit 33 so that the signal amplitude of the corresponding XI, XQ, YI, and YQ signals is in the optimum range. Then, back in step S 11 , it is repeatedly determined whether or not the extraction of constellation and each signal amplitude are in the optimum range.
- step S 15 it is determined using the determining method as described with reference to FIG. 8 whether or not the inter-IQ skew of the acquisition value of each signal is in the preset optimum range. If the determination in step S 15 is NO and it is not in the optimum range, then the compensation is performed in step S 16 through the skew control unit 35 so that the amount of skew of the corresponding XI, XQ, YI, and YQ signals maybe in the optimum range.
- step S 17 the signal amplitude at the output of the O/E converter 25 on the reception side is adjusted for the optimum range through the amplitude control unit 33 for each signal of XI, XQ, YI, and YQ, and then control is returned to step S 14 .
- the extraction of the constellation and the determination as to whether or not the inter-IQ skew of each signal is in the optimum range are repeated, and if the determination in step S 15 is YES, the process terminates.
- FIG. 11 is a flowchart of the process of the amplitude control amount determination unit in FIG. 9 .
- step S 20 as the initialization, the set value indicating the range of the amplitude determination mask A is stored in the variable Mask_Cons_A.
- the set value indicating the range of the amplitude determination mask B is stored in the variable Mask_Cons_B.
- the set value indicating the range of the amplitude determination mask C is stored in the variable Mask_Cons_C.
- the threshold for determination of excessive amplitude is stored in the variable Amp_Std_Coeff_over.
- the threshold for determination of too small amplitude is stored in the variable Amp_Std_Coeff_under.
- step S 21 the amplitude set value of the XI signal (set value for the output amplitude of the O/E converter 25 ) is stored in the variable AMP_XI.
- the amplitude set value of the XQ signal (set value for output amplitude of the O/E converter 25 ) is stored in the variable AMP_Step_XQ.
- the amplitude change amount set value of the XI signal is stored in the AMP_Step_XI.
- the amplitude change amount set value of the XQ signal is stored in the variable AMP_Step_XQ.
- step S 22 the constellation information about the X polarization read from the capture unit A 30 is stored in the variable Meas_Cons_X.
- step S 23 the number of signal points in each mask is counted on Meas_Cons_X using Mask_Cons_A, Mask_Cons_B, and Mask_Cons_C, thereby obtaining the two ratios described with reference to FIG. 7 .
- the ratio for determination of excessive amplitude is stored in the variable Amp_Meas_Coeff_over.
- the ratio for determination of too small amplitude is stored in Amp_Meas_Coeff_under.
- step S 26 If the determination in step S 26 is NO, the same process (process A) as steps S 21 through S 27 is performed on the Y polarization component in step S 28 , and the process terminates when the amplitude is appropriate.
- FIG. 12 is a flowchart of the process of the EVM determination unit in FIG. 9 .
- step S 30 as the initialization, the vector indicating the ideal signal point position is set as a reference vector, and stored in the variable Std_Vector.
- step S 31 the process is performed from the X polarization component.
- step S 31 according to the constellation information about the X polarization read from the capture unit B 31 , the actually measured vector is calculated, and stored in the variable Meas_Vector_X.
- Meas_Vector_X In this example, for example, in the QPSK, four signal points appear on the I-Q plane.
- the reference vector is to be expected as a vector of the ideal signal point in the first quadrant.
- step S 32 the vector difference is calculated by Std_Vector and Meas_Vector_X, and stored in the variable EVM_Vector_X.
- step S 33 the XI amplitude error is calculated from EVM_Vector_X, and stored in the variable Amp_Error_XI.
- the XQ amplitude error is calculated and stored in the variable Amp_Error_XQ.
- the inter-IQ phase error is calculated, and stored in the variable Phase_Error_X.
- step S 34 the multiplexing unit 22 adjusts the phase of the XI and XQ signals using the half value of Phase_Error_X.
- step S 35 the O/E converter 25 on the reception side adjusts the phase of the XI and XQ signals using the half value of Phase_Error_X as the amount of compensation.
- step S 36 the O/E converter 25 performs amplitude control using the amplitude control unit 33 according to the values of Amp_Error_XI and Amp_Error_XQ as the amount of compensation, thereby passing control to step S 37 .
- step S 37 the same process (process A) as in steps S 31 through S 36 is performed on the Y polarization signal, and the process terminates.
- the amplitude variance of each signal and the inter-IQ skew amount may be detected in each polarization unit according to the constellation information extracted from the capture unit. Using these parameters, the amplitude compensation or the inter-IQ skew compensation is performed, thereby successfully improving the performance of the digital optical coherent receiver.
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Optical Communication System (AREA)
- Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
Abstract
Description
- 1) the reduction of the tolerancce relating to an optical signal to noise ratio;
- 2) an insufficient band of the wavelength filter during the WDM (wavelength division multiplexing) transmission;
- 3) the wavelength dispersion of a transmission line, a waveform distortion by a nonlinear effect, etc.
EVM(n)=√I error(n)2 +Q error(n)2*(n)=measurement at symbol time [Math 1]
Claims (7)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2012-075172 | 2012-03-28 | ||
JP2012075172A JP5888056B2 (en) | 2012-03-28 | 2012-03-28 | Digital optical coherent transmission device |
Publications (2)
Publication Number | Publication Date |
---|---|
US20130259487A1 US20130259487A1 (en) | 2013-10-03 |
US9031420B2 true US9031420B2 (en) | 2015-05-12 |
Family
ID=47747388
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/759,214 Active 2033-07-13 US9031420B2 (en) | 2012-03-28 | 2013-02-05 | Digital optical coherent transmission device |
Country Status (3)
Country | Link |
---|---|
US (1) | US9031420B2 (en) |
EP (1) | EP2645601B1 (en) |
JP (1) | JP5888056B2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10547408B2 (en) * | 2018-05-03 | 2020-01-28 | Juniper Networks, Inc. | Methods and apparatus for improving the skew tolerance of a coherent optical transponder in an optical communication system |
Families Citing this family (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2014239309A (en) * | 2013-06-06 | 2014-12-18 | 富士通オプティカルコンポーネンツ株式会社 | Optical transmitter, optical receiver, and optical transmitter receiver |
JP6156058B2 (en) * | 2013-10-28 | 2017-07-05 | ソニー株式会社 | Receiving device, receiving method, and program |
US9882653B2 (en) * | 2015-04-10 | 2018-01-30 | Arista Networks, Inc. | System and method of de-skewing electrical signals |
CN107919905B (en) * | 2016-10-10 | 2020-05-22 | 富士通株式会社 | Device and method for measuring unbalance of frequency response characteristics of optical receiver |
JP6919361B2 (en) * | 2017-06-26 | 2021-08-18 | 富士通株式会社 | Optical receiver, optical transmitter, optical communication system, and skew adjustment method |
JP7100432B2 (en) * | 2017-08-17 | 2022-07-13 | 富士通オプティカルコンポーネンツ株式会社 | Optical transmission device and optical transmission method |
US10601521B2 (en) * | 2018-05-14 | 2020-03-24 | Nokia Solutions And Networks Oy | Coherent optical communication with constellations having coordinates on circles |
CN109787691B (en) * | 2018-11-28 | 2021-01-08 | 武汉光迅科技股份有限公司 | Parameter determination method, equipment and computer storage medium |
CN111585646B (en) * | 2019-02-19 | 2023-03-31 | 富士通株式会社 | Estimation device and method for relative time delay of polarization state |
JP2019180091A (en) * | 2019-06-07 | 2019-10-17 | 富士通株式会社 | Receiver unit and reception method |
JP7158344B2 (en) * | 2019-06-21 | 2022-10-21 | 旭化成エレクトロニクス株式会社 | demodulator |
WO2023175815A1 (en) * | 2022-03-17 | 2023-09-21 | 三菱電機株式会社 | Optical receiving device |
Citations (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006352525A (en) | 2005-06-16 | 2006-12-28 | Matsushita Electric Ind Co Ltd | Communication device and correction table creation method |
US20070147850A1 (en) * | 2003-04-29 | 2007-06-28 | Savory Seb J | Digital Compensation for Optical Transmission System |
EP1959590A2 (en) | 2007-02-16 | 2008-08-20 | Fujitsu Ltd. | Analog-to-digital conversion controller, optical receiving device, optical receiving method, and waveform-distortion compensating device |
EP1962443A1 (en) | 2007-02-26 | 2008-08-27 | Fujitsu Ltd. | Digital phase estimator, digital phase loked loop and optical coherent receiver |
US20080267638A1 (en) * | 2007-04-27 | 2008-10-30 | Fujitsu Limited | Optical receiver |
US20090214201A1 (en) | 2008-02-22 | 2009-08-27 | Fujitsu Limited | Monitor circuit for monitoring property of optical fiber transmission line and quality of optical signal |
JP2010080665A (en) | 2008-09-26 | 2010-04-08 | Nec Corp | Device and method for receiving light |
US20100209121A1 (en) * | 2009-02-18 | 2010-08-19 | Fujitsu Limited | Signal processing device and optical receiving device |
EP2224659A1 (en) | 2009-02-26 | 2010-09-01 | Alcatel Lucent | Power manageable optical OFDM transporter |
JP2010226254A (en) | 2009-03-19 | 2010-10-07 | Nippon Telegr & Teleph Corp <Ntt> | Digital signal processing circuit and optical receiving device |
EP2357740A1 (en) | 2010-02-12 | 2011-08-17 | Fujitsu Limited | Optical receiver |
US20110229127A1 (en) | 2010-03-19 | 2011-09-22 | Fujitsu Limited | Digital coherent receiver and digital coherent reception method |
US8068742B2 (en) * | 2008-07-10 | 2011-11-29 | Finisar Corporation | Phase shift keyed modulation of optical signal using chirp managed laser |
US20130051809A1 (en) * | 2011-08-24 | 2013-02-28 | Hamid Mehrvar | Short-term optical recovery systems and methods for coherent optical receivers |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5407265B2 (en) * | 2008-10-09 | 2014-02-05 | 富士通株式会社 | Optical receiver and optical receiving method |
US8184731B2 (en) * | 2009-02-17 | 2012-05-22 | Nec Laboratories America, Inc. | Feedback adjustable constellation de-mapper |
JP5365315B2 (en) * | 2009-04-03 | 2013-12-11 | 富士通株式会社 | Optical receiver and optical receiving method |
WO2012003856A1 (en) * | 2010-07-05 | 2012-01-12 | Nokia Siemens Networks Oy | Method and device for data processing in an optical communication network |
-
2012
- 2012-03-28 JP JP2012075172A patent/JP5888056B2/en active Active
-
2013
- 2013-02-04 EP EP13153812.6A patent/EP2645601B1/en active Active
- 2013-02-05 US US13/759,214 patent/US9031420B2/en active Active
Patent Citations (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20070147850A1 (en) * | 2003-04-29 | 2007-06-28 | Savory Seb J | Digital Compensation for Optical Transmission System |
JP2006352525A (en) | 2005-06-16 | 2006-12-28 | Matsushita Electric Ind Co Ltd | Communication device and correction table creation method |
EP1959590A2 (en) | 2007-02-16 | 2008-08-20 | Fujitsu Ltd. | Analog-to-digital conversion controller, optical receiving device, optical receiving method, and waveform-distortion compensating device |
EP1962443A1 (en) | 2007-02-26 | 2008-08-27 | Fujitsu Ltd. | Digital phase estimator, digital phase loked loop and optical coherent receiver |
US20080267638A1 (en) * | 2007-04-27 | 2008-10-30 | Fujitsu Limited | Optical receiver |
US20090214201A1 (en) | 2008-02-22 | 2009-08-27 | Fujitsu Limited | Monitor circuit for monitoring property of optical fiber transmission line and quality of optical signal |
JP2009198364A (en) | 2008-02-22 | 2009-09-03 | Fujitsu Ltd | Monitor circuit for monitoring property of optical fiber transmission line and quality of optical signal |
US8068742B2 (en) * | 2008-07-10 | 2011-11-29 | Finisar Corporation | Phase shift keyed modulation of optical signal using chirp managed laser |
JP2010080665A (en) | 2008-09-26 | 2010-04-08 | Nec Corp | Device and method for receiving light |
US20100209121A1 (en) * | 2009-02-18 | 2010-08-19 | Fujitsu Limited | Signal processing device and optical receiving device |
EP2221999A1 (en) | 2009-02-18 | 2010-08-25 | Fujitsu Limited | Signal processing device and optical receiving device |
EP2224659A1 (en) | 2009-02-26 | 2010-09-01 | Alcatel Lucent | Power manageable optical OFDM transporter |
JP2010226254A (en) | 2009-03-19 | 2010-10-07 | Nippon Telegr & Teleph Corp <Ntt> | Digital signal processing circuit and optical receiving device |
EP2357740A1 (en) | 2010-02-12 | 2011-08-17 | Fujitsu Limited | Optical receiver |
US20110229127A1 (en) | 2010-03-19 | 2011-09-22 | Fujitsu Limited | Digital coherent receiver and digital coherent reception method |
US20130051809A1 (en) * | 2011-08-24 | 2013-02-28 | Hamid Mehrvar | Short-term optical recovery systems and methods for coherent optical receivers |
Non-Patent Citations (1)
Title |
---|
Extended European Search Report dated Jul. 11, 2013 issued in corresponding European Patent Application No. 13153812.6. |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10547408B2 (en) * | 2018-05-03 | 2020-01-28 | Juniper Networks, Inc. | Methods and apparatus for improving the skew tolerance of a coherent optical transponder in an optical communication system |
US10917191B2 (en) | 2018-05-03 | 2021-02-09 | Juniper Networks, Inc. | Methods and apparatus for improving the skew tolerance of a coherent optical transponder in an optical communication system |
Also Published As
Publication number | Publication date |
---|---|
EP2645601B1 (en) | 2018-08-01 |
US20130259487A1 (en) | 2013-10-03 |
JP5888056B2 (en) | 2016-03-16 |
JP2013207603A (en) | 2013-10-07 |
EP2645601A1 (en) | 2013-10-02 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US9031420B2 (en) | Digital optical coherent transmission device | |
US20180145761A1 (en) | Low-Latency Adjustment of Flexible Transceivers using Pilot Signal | |
US9564976B2 (en) | Blind equalization of dual subcarrier OFDM signals | |
JP5922670B2 (en) | System and method for generating soft decision reliability information from hard decision in an optical signal receiver | |
US8340534B2 (en) | Side band pilot tone for digital signal processing in polarization multiplexed coherent optical communication system | |
EP2930865B1 (en) | Transmitter quadrature imbalance compensation at a coherent optical receiver | |
JP5287516B2 (en) | Digital coherent optical receiver | |
EP2583424B1 (en) | Method for phase and oscillator frequency estimation | |
GB2538141A (en) | Channel performance monitoring and an optical communication system using same | |
US20140099108A1 (en) | System and method for heterodyne coherent detection with optimal offset | |
US8428468B2 (en) | Polarization multiplexing optical transmission system, polarization multiplexing optical receiver and polarization multiplexing optical transmission method | |
US20190109648A1 (en) | Digital optical receiver and optical communication system using the same | |
US9571224B2 (en) | Transmission device, receiving device, and communication method | |
CN108076002B (en) | Offset drift compensation device, received signal recovery device, and receiver | |
US9270383B2 (en) | Frequency and phase compensation for modulation formats using multiple sub-carriers | |
US9467318B2 (en) | Communication system, receiving device, and semiconductor device | |
US9219550B2 (en) | Forward carrier recovery using forward error correction (FEC) feedback | |
US20140233949A1 (en) | Optical communication based on polarization dependent coherent optical nyquist frequency division multiplexing | |
JP2017507510A (en) | System and method for cycle slip correction | |
CN111095823B (en) | Optical transmitter/receiver and optical transmitting/receiving method | |
JP2013229783A (en) | Optical transceiver and optical transmission/reception method | |
Walsh et al. | Demonstrating doubly-differential quadrature phase shift keying in the optical domain | |
US9276674B2 (en) | Estimating phase using test phases and interpolation for modulation formats using multiple sub-carriers | |
EP4099584B1 (en) | Mitigation of equalization-enhanced phase noise in a coherent optical receiver | |
EP3240226A1 (en) | Method and apparatus for transmitting data in a super channel |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: SOUNDHOUND, INC., CALIFORNIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:MCMAHON, KATHLEEN WORTHINGTON;MONT-REYNAUD, BERNARD;REEL/FRAME:029162/0705 Effective date: 20121017 |
|
AS | Assignment |
Owner name: FUJITSU LIMITED, JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SAKAMOTO, YUICHIROU;REEL/FRAME:029781/0780 Effective date: 20121001 |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
MAFP | Maintenance fee payment |
Free format text: PAYMENT OF MAINTENANCE FEE, 4TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1551); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY Year of fee payment: 4 |
|
AS | Assignment |
Owner name: SILICON VALLEY BANK, CALIFORNIA Free format text: SECURITY INTEREST;ASSIGNOR:SOUNDHOUND, INC.;REEL/FRAME:055807/0539 Effective date: 20210331 |
|
AS | Assignment |
Owner name: SOUNDHOUND, INC., CALIFORNIA Free format text: SECURITY INTEREST;ASSIGNOR:OCEAN II PLO LLC, AS ADMINISTRATIVE AGENT AND COLLATERAL AGENT;REEL/FRAME:056627/0772 Effective date: 20210614 |
|
MAFP | Maintenance fee payment |
Free format text: PAYMENT OF MAINTENANCE FEE, 8TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1552); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY Year of fee payment: 8 |
|
AS | Assignment |
Owner name: OCEAN II PLO LLC, AS ADMINISTRATIVE AGENT AND COLLATERAL AGENT, CALIFORNIA Free format text: CORRECTIVE ASSIGNMENT TO CORRECT THE COVER SHEET PREVIOUSLY RECORDED AT REEL: 056627 FRAME: 0772. ASSIGNOR(S) HEREBY CONFIRMS THE SECURITY INTEREST;ASSIGNOR:SOUNDHOUND, INC.;REEL/FRAME:063336/0146 Effective date: 20210614 |
|
AS | Assignment |
Owner name: SOUNDHOUND, INC., CALIFORNIA Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:OCEAN II PLO LLC, AS ADMINISTRATIVE AGENT AND COLLATERAL AGENT;REEL/FRAME:063380/0625 Effective date: 20230414 |
|
AS | Assignment |
Owner name: SOUNDHOUND, INC., CALIFORNIA Free format text: RELEASE BY SECURED PARTY;ASSIGNOR:FIRST-CITIZENS BANK & TRUST COMPANY, AS AGENT;REEL/FRAME:063411/0396 Effective date: 20230417 |